Silicon Tetrafluoride Elements-manufacture,factory,supplier from China

In recent years, China's polysilicon production has shown geometric development, but the disposal of polysilicon by-product silicon tetrachloride has become a difficult to step over the development of polysilicon industry "sill", let the silicon industry wear the hat of high pollution.

In silicon tetrachloride purification, boron is the most difficult impurity to remove. Researchers have proposed compound method to remove boron from silicon tetrachloride, which has achieved satisfactory results and has been widely used in industrial production.

The basic principle of solid adsorption is adsorption separation based on the different polarity of chemical bonds of each component in a compound. Silicon tetrachloride is a symmetric molecule with no dipole moment. In contrast, the contained impurities such as BCl3, AlCl3, FeCl3, PCl3, etc. are asymmetric molecules with considerable dipole moments, which strongly tend to form additive chemical bonds and are easily adsorbed by the adsorbent.

Silicon tetrachloride is an important chemical raw material, it is widely used to produce high-purity silicon, silane, silicone ester, silicone oil, silica gel and other products, widely used in ink, paint, resin, rubber, medicine, grease and other fields; Silicon tetrachloride can also be used to manufacture optical fiber, polysilicon, silicon dioxide, etc., in communications, photovoltaic power generation, optical instruments and other fields of application; In addition, silicon tetrachloride can also be used in the military field, metallurgy, casting and other fields.

Distillation is the use of SiCl4, and the difference between the relative volatility of impurities components, through several partial gasification and partial condensation process, to achieve the separation of mixed liquid, so as to obtain high purity silicon tetrachloride products.

The main by-product of trichlorosilane, silicon tetrachloride, is also the main raw material for the manufacture of silicone, its finished products are silicone ester, silicone oil, high temperature insulating paint, silicone resin, silicone rubber and heat resistant cushion lining materials. High purity silicon tetrachloride is also an important raw material for manufacturing high purity silicon dioxide, inorganic silicon compounds, quartz fibers and optical fibers.

SiCl4 is one of the most important inorganic silicon compounds, is a colorless, transparent, flowing smoke liquid, with suffocating odor, soluble in benzene, ether, chloroform and other most organic solvents. Silicon tetrachloride is a volatile liquid with strong asphyxiating odor. It can be used as raw materials for the production of gaseous silica, high purity silicon and organosilicide. The upstream of the silicon tetrachloride industry chain is the raw material market, mainly silicon powder, ferrosilicon, hydrogen chloride, etc.

Silicon tetrachloride which chemical formula is SiCl4 is an inorganic compound, because silicon chloride only exists in the form of SiCl4, silicon tetrachloride is also directly called silicon chloride. The appearance of this product is light yellow liquid, and the appearance of high-purity silicon tetrachloride is colorless and transparent liquid, volatile, with special odor, toxicity and corrosion. Silicon tetrachloride can be miscible with benzene, chloroform, ether, carbon tetrachloride and other organic solvents. It can be hydrolyzed in humid air and react violently with water.

Silicon tetrachloride is mainly used in the manufacture of silicone esters, gaseous silica, silicone monomer, silicone oil, high temperature insulating paint, silicone resin, silicone rubber and so on. High-purity silicon tetrachloride is the main raw material for manufacturing fiber prefabricated rod, and the quality of fiber prefabricated rod directly determines the fiber performance. Therefore, high-purity silicon tetrachloride is the core raw material of fiber industry.

Chlorine hydrogenation technology is to add HCl on the basis of low temperature hydrogenation technology to further reduce the reaction temperature and increase the yield of trichlorosilane. Chlorine hydrogenation reaction principle is as follows: 2SiCl4(g)+H2(g)+HCl(g)+Si(s)=3SiHCl3(g). Hydrogen plasma is generated by hydrogen discharge, which is passed into the reactor to react with silicon tetrachloride gas. Since hydrogen is dissociated into hydrogen atoms, the reactivity is greatly increased and it can easily react with silicon tetrachloride to form trichlorosilane.

High temperature hydrogenation of silicon tetrachloride is an important method to treat silicon tetrachloride as a by-product of polysilicon. High temperature hydrogenation is silicon tetrachloride and hydrogen as raw materials, heated by 1200 ~ 1250℃ graphite heater, thermal reduction reaction to produce  trichlorosilane. The advantages of the process are that the whole system is closed circulation, suitable for continuous and stable operation; Trichlorosilane products of high purity, need to distillation links less.

Silicon tetrachloride is an important raw material and intermediate product in the process of organic silicon synthesis and polysilicon production. Under different environmental conditions, silicon tetrachloride can react with a variety of substances to produce new substances.

Since May 2022, trichlorosilane has been sustained upward by the downward trend in silicon metal prices.

The principle is to reduce high purity trichlorosilane with high purity hydrogen on the high purity silicon core at about 1100℃ to generate polycrystalline silicon deposited on the silicon core. On the basis of the traditional Siemens process, the improved Siemens process is equipped with a supporting process of energy saving, consumption reduction, recycling and utilization of a large amount of H2, HCI, SiCI4 and other by-products and a large amount of by-production heat energy.

The production process of trichlorosilane is mostly prepared by reaction of gold-grade silicon metal powder and hydrogen chloride gas in a fluidized bed reactor. Generally using gold grade metal silicon powder, hydrogen chloride gas by the combustion reaction of chlorine and hydrogen gas. Reaction temperature is 300-400 degrees, most of the pressure using micro positive pressure operation.

Trichlorosilane (TCS or SiHCl3) is generated as follows within a high temperature, pressurized reactor: Si + 3 HCl ➡ SiHCl3 + H2 ，Si + 3 SiCl4 +2 H2 ➡ 4 SiHCl3 .The TCS is then sent to the CVD (Chemical Vapor Desposition) reactor. In the Siemens process, high-purity silicon "starter" rods or hairpins are exposed to trichlorosilane at 1150 °C in the CVD reactor.

At present, there are two main synthesis methods of trichlorosilane: one is the traditional synthesis method, that is the silicon chloride method. The other is hydrolyzation of tetrachloride. At present, the mainstream method of polysilicon production is the modified Siemens method, using trichlorosilane reduction method. In recent years, with the continuous decline of polysilicon price, polysilicon production enterprises pay more and more attention to the control of production cost.

Devices that use tail gas to recover cyclohexylamine are characterized in that they include: spray tower, circulating pump, condenser, defogger, photooxygen catalytic oxidizer, ozone treatment device, blower, chimney. Described in the circulating pump and spray the bottom connection, as described in the other side of the circulating pump are connected to the condenser, the condenser and the upper spray tower connection, described in the spray tower are connected to the top of demister, described in the mist bottom and photocatalytic oxidation, photocatalytic oxidation is described, ozone

The purity of hydrogen is high, and the purity of cyclohexylamine reaches over 99.95%, which is higher than the industry standard by 99.8%. The purity of dicyclohexylamine is higher than 99.5%, which is 99% higher than the standard of peer enterprises. Recycling the industrial chain can reduce the comprehensive cost of the factory. There are three aniline factories in Dongying, Shandong, Huai 'an, Jiangsu and Tianji, Shanxi within 400 kilometers. The technology is mature, and the workers have about twenty years of practical experience.

Cyclohexylamine has the chemical properties of a primary amine. Carbonates that are strongly alkaline and absorb carbon dioxide in the air to form white crystals. It can react with acyl chloride, anhydride and ester to form N-acyl. React with nitrite to give alcohol. Hydroxymethyl compounds are formed by reaction with formaldehyde in alkaline solution. Reacts with carbon disulfide to form dithiocarbamate. Reacts with aldehydes to form Schiff bases.This product is used to prepare cyclohexanol, caprolactam, acetate fiber and nylon 6, etc.

It is obtained by catalytic reduction of nickel or cobalt from aniline at high temperature and pressure. Cyclohexanol can also be reduced by phenol, oxidized to cyclohexanone, and then aminated with ammonia to obtain cyclohexanamine.This substance is harmful to the environment, and special attention should be paid to the pollution of water bodies. Acute poisoning may occur by inhalation of vapour. Irritant and corrosive to skin, eyes and mucous membranes, and can cause allergy through skin absorption.

It is obtained by catalytic hydrogenation of aniline and can be divided into atmospheric pressure method and pressure method. In addition, cyclohexamine can be prepared by catalytic ammonolysis of cyclohexane or cyclohexanol, reduction of nitrocyclohexane, and catalytic ammonolysis of cyclohexanone in the presence of hydrogen.The refining process often contains impurities such as aniline and water.

The method of species co-production of cyclohexylamine and dicyclohexylamine and the catalyst system used for the method. The method includes the following steps :(1) the raw material aniline, cyclohexanone, ammonia, hydrogen after the loading load RhNi catalyst first section reactor, the first reaction liquid.(2) The reaction solution containing cyclohexylamine and dicyclohexylamine was obtained through the second stage reactor loaded with RhCo catalyst.

DCHA at home and abroad is usually a by-product of CHA production. In the process of CHA synthesis by aniline hydrogenation, about 10% of DCHA can be obtained by by-product. In addition, according to the different catalysts, the yield of DCHA prepared by aniline hydrogenation can reach up to 70%, and the yield of cyclohexylamine (CHA) is 30%.Benzene, cyclohexane, cyclohexanol, N-cyclohexylcyclohexamine, phenylcyclohexylamine and other by-products will be generated in the reaction.